Electric heating element for hot-water bottles



Sept. 10, 1929. A, svENN Er AL ELECTRIC HEATING ELEMENT `FOR HOT WATERBOTTLES Filed June 9, 1928 Patented Sept. 10, 1929'.

UNITED STATES PATENT OFFICE.

EECTRIO HEATING ELEMENT FOR HOT-WATER BOTTLES.

Application `1114511 .Tune 9,

This invention relates to improvements i'n an electric heating elementfor a hot water bottle or the like and has for one of its principalobjects the provision of means for maintaining the water in the bag at aconstant warm temperature when the bag 1s being used, and forautomatically disconnecting the current supply when the bag is not beingused.

One of the important objects of the invention is to provide acombination hot water bottle stopper and electric heating element whichextends into the bag and makes contact with the water contained thereinand heats the same when the bag is in a prone position and which willshut off the current supply when thebag is in an uprlght positlon.

Another important object of the invention is the provision of anautomatic switch for a hot water bag heating element which is fool proofand cannot possibly be tampered with or become out of order.

Other and further important objects of the invention will be apparentfrom the disclosures in the accompanying drawings and followingspecification. e

The invention, in a preferred/form, is illustrated in the drawings andhereinafter more fully described.

In' the drawings:

Figure l is a vertical sectional View of the combination hot waterbottle plug and heating element, the electrical circuit being shown inopen position.

Figure 2 is a fragmentary sectional view of the plug and heating elementmounted in al hot water bottle, the electrical circuit being closed.

As shown in the drawings:

The reference numeral 10 indicates generally the usual hot water bottle,constructed of rubber or such like material, having an internallythreaded neck 12 adapted to engage threads 14 of a stopper 16, which inthis case, is a combination plug and heating element.

The upper portion 18 of the plug is constructed of fibre, hard rubber orsome other like insulating material and embedded therein and extendingupwardly therefrom are two contact making prongs 2O and 20, adapt- 1928.Serial No. 284,095.

ed to be inserted in a usual electric connecting plug 22.

The lower portion of the plug 16 terminates in a `completely enclosedwaterproof cylindrical casing 24, constructed of brass or some suchnon-rusting material. Contained within the cylindrical casing 24 is adepending metallic rod 26 coveredwith an insulating material 28 such asmica or the like. A heating coil 30 is wound upon the rod 26 and isinsulated from the said rod by the insulation 28, the lower terminal ofthe said coil being connected to the lower end of the rod.

The member 16 is provided with a cylindrical opening 32, into which ametallic mem- 65 ber 34 is threadedly positioned. The rod 26 isthreadedly mounted in the member 34 and makes electrical contacttherewith. The diameter of the member 34 is smaller than the diameter ofthe cylindrical opening 32 and is adapted to be submerged in a mercurybat-h 36. The quantity of mercury used is suficient to cover the top ofthe member 34 when the plug is in an upright position, as shown best inFigure 1, but is not sufficient to reach the top of the opening 32,which comprises an integral portion of the prong 20a.

The prong 20 is connected directly to the heating element 30 by meansofa connector 38. Hence, it is apparent that when the plug is suiicientlytilted the mercury will brldge the ap between the upper portion of themem er 34 and the lower portion of the prong 20a thus completing theelectrical circuit, as shown in Figure 2.

A hot water bottle is usually used ina prone position, as shown best inFigure 2, therefore, the heating element is energized by the bridgingofthe gap between the member 34 and the prong 20a.

A bushing or washer 4() constructed of some resilient substance makes awater-tight closure upon the bag, and as an added safety measure theinner surface of the member 24 is lined with insulating material 42which 95 eliminates any possibility of short circuiting or grounding theheating coil 30. The space around the coil 30 may be filled with anelectrical insulator, if desired.

It is apparent that herein is provided a 100v device which is bothrugged and efficient. It can be readily manufactured and economicallymarketed and will appeal to anyone who has had the annoying experienceof con- 5 tinually refilling a hot water bottle to keep the same at adesired temperature.

We are aware that many changes may be made and numerous details ofconstruction varied throughout a wide range without dem parting from theprinciples of this invention, and we therefore do not propose limitingthe patent granted hereon otherwise than as necessitated by the priorart.

We claim as our invention:

A combination hot Water bag sto per and heating element, including athrea ed plug, an integral extension dependin from the bottom of theplug, a heating e ement contained Within the extension, a pair ofContact prongs projecting from the top of the plug, one terminus of theheating element being connected to one of the prongs, the other end ofthe heating element terminating in a contacting member, a mercury bathenveloping the up er portion of the contacting member, the ot er prongbeing adjacent the upper portion o the mercury bath. i

In testimony whereof we affix our signatures. i

ALFRED SVENN.

ARTHUR 'SODERHOLNL

